Swift follow-up of IceCube triggers, and implications for the Advanced-LIGO era

Between 2011 March and 2014 August Swift responded to 20 triggers from the IceCube neutrino observatory, observing the IceCube 50% confidence error circle in X-rays, typically within 5 hours of the trigger. No confirmed counterpart has been detected. We describe the Swift follow up strategy and data analysis and present the results of the campaign. We discuss the challenges of distinguishing the X-ray counterpart to a neutrino trigger from serendipitous uncatalogued X-ray sources in the error circle, and consider the implications of our results for future strategies for multi-messenger astronomy, with particular reference to the follow up of gravitational wave triggers from the advanced-era detectors.Comment: Accepted for publication in MNRAS. 18 pages, including 8 figures and 4 tables; two of which are landscape-oriente

Effects of site management in pine plantations on the coastal lowlands of subtropical Queensland, Australia

Biomass and nutrient distribution in a 30-year-old slash pine (Pinus elliottii) plantation in Queensland, Australia, were estimated following clear-felling in November 1995, to provide a basis for interpreting changes in the nutrient pools and tree responses to harvest residue management practices applied at the establishment of the second rotation. Total biomass at clearfall of a typical slash pine stand was 316 t ha-1, of which 206 t ha-1 was removed in logs. Nitrogen and P removed in logs accounted for 7.6 and 3.4% of total N and P, respectively, in the ecosystem. Residues remaining after logging contained 12% of the total N and 5.2% of the total P. Proper management of these residues is therefore critical for sustaining site productivity. Following clear felling, a long-term experiment was established to assess the impacts of harvesting residues and litter management regimes on soil fertility and productivity of the second crop F1 hybrid between slash pine and Honduras Caribbean pine (P. caribaea var. hondurensis). Early results from this experiment showed that tree stem volume and above ground biomass production increased by 31 and 29%, respectively, at age 39 months by retaining litter and logging residues, compared with the treatment in which logging residues and litter were removed. Further improvements in tree growth have been achieved by doubling the quantity of residues retained and by controlling weed competition. Foliar nutrient concentrations indicated that N may play an important role in the maintenance of long-term site productivity. Differences exist in the growth and foliar nutrient concentrations between the different hybrid families tested but all families responded similarly to the residue treatments. The presence of the residues increased soil moisture levels in the surface soil during a dry season. There was a marked reduction in the quantity of residue, especially the finer fraction, after 39 months. This study has contributed to an improved understanding of the soil and plant factors controlling productivity and provided a basis for more detailed studies on processes underpinning plantation sustainability

Expansion of the ligand knowledge base for chelating P,P-donor ligands (LKB-PP)

[Image: see text] We have expanded the ligand knowledge base for bidentate P,P- and P,N-donor ligands (LKB-PP, Organometallics2008, 27, 1372–1383) by 208 ligands and introduced an additional steric descriptor (nHe(8)). This expanded knowledge base now captures information on 334 bidentate ligands and has been processed with principal component analysis (PCA) of the descriptors to produce a detailed map of bidentate ligand space, which better captures ligand variation and has been used for the analysis of ligand properties

Information Leakage Games

We consider a game-theoretic setting to model the interplay between attacker and defender in the context of information flow, and to reason about their optimal strategies. In contrast with standard game theory, in our games the utility of a mixed strategy is a convex function of the distribution on the defender's pure actions, rather than the expected value of their utilities. Nevertheless, the important properties of game theory, notably the existence of a Nash equilibrium, still hold for our (zero-sum) leakage games, and we provide algorithms to compute the corresponding optimal strategies. As typical in (simultaneous) game theory, the optimal strategy is usually mixed, i.e., probabilistic, for both the attacker and the defender. From the point of view of information flow, this was to be expected in the case of the defender, since it is well known that randomization at the level of the system design may help to reduce information leaks. Regarding the attacker, however, this seems the first work (w.r.t. the literature in information flow) proving formally that in certain cases the optimal attack strategy is necessarily probabilistic

Multi-epoch Doppler tomography and polarimetry of QQ Vul

We present multi-epoch high-resolution spectroscopy and photoelectric polarimetry of the long-period polar (AM Herculis star) QQ Vul. The blue emission lines show several distinct components, the sharpest of which can unequivocally be assigned to the illuminated hemisphere of the secondary star and used to trace its orbital motion. This narrow emission line can be used in combination with Nai-absorption lines from the photosphere of the companion to build a stable long-term ephemeris for the star: inferior conjunction of the companion occurs at HJD = 244 8446.4710(5)+E×0. d 15452011(11). The polarization curves are dissimilar at different epochs, thus supporting the idea of fundamental changes of the accretion geometry, e.g. between one- and two-pole accretion modes. The linear polarization pulses display a random scatter by 0.2 phase units and are not suitable for the determination of the binary period. The polarization data suggest that the magnetic (dipolar) axis has a co-latitude of 23 ◦ , an azimuth of −50 ◦, and an orbital inclination between 50 ◦ and 70 ◦. Doppler images of blue emission and red absorption lines show a clear separatio

'I would rather die': reasons given by 16-year-olds for not continuing their study of mathematics

Improving participation rates in specialist mathematics after the subject ceases to be compulsory at age 16 is part of government policy in England. This article provides independent and recent support for earlier findings concerning reasons for non- participation, based on free response and closed items in a questionnaire with a sample of over 1500 students in 17 schools, close to the moment of choice. The analysis supports findings that perceived difficulty and lack of confidence are important reasons for students not continuing with mathematics, and that perceived dislike and boredom, and lack of relevance, are also factors. There is a close relationship between reasons for non-participation and predicted grade, and a weaker relation to gender. An analysis of the effects of schools, demonstrates that enjoyment is the main factor differentiating schools with high and low participation indices. Building on discussion of these findings, ways of improving participation are briefly suggested

From X-ray dips to eclipse: Witnessing disk reformation in the recurrent nova USco

The 10th recorded outburst of the recurrent eclipsing nova USco was observed simultaneously in X-ray, UV, and optical by XMM-Newton on days 22.9 and 34.9 after outburst. Two full passages of the companion in front of the nova ejecta were observed, witnessing the reformation of the accretion disk. On day 22.9, we observed smooth eclipses in UV and optical but deep dips in the X-ray light curve which disappeared by day 34.9, then yielding clean eclipses in all bands. X-ray dips can be caused by clumpy absorbing material that intersects the line of sight while moving along highly elliptical trajectories. Cold material from the companion could explain the absence of dips in UV and optical light. The disappearance of X-ray dips before day 34.9 implies significant progress in the formation of the disk. The X-ray spectra contain photospheric continuum emission plus strong emission lines, but no clear absorption lines. Both continuum and emission lines in the X-ray spectra indicate a temperature increase from day 22.9 to day 34.9. We find clear evidence in the spectra and light curves for Thompson scattering of the photospheric emission from the white dwarf. Photospheric absorption lines can be smeared out during scattering in a plasma of fast electrons. We also find spectral signatures of resonant line scattering that lead to the observation of the strong emission lines. Their dominance could be a general phenomenon in high-inclination systems such as Cal87.Comment: Submitted to ApJ. 16 pages, 16 figure

What do we know about the nexus between culture, age, gender and health literacy? Implications for improving the health and well-being of young Indigenous males

Health literacy, although diversely defined, refers to the abilities, relationships and external environments required for people to successfully promote health. Existing research suggests that health literacy is related to health inequities, including individual and community capacity to navigate health. A diverse range of factors shape health literacy abilities and environments, especially culture, gender and age. However, the nexus between these variables and their cumulative impact on health literacy development remains largely unexplored. Commentary that explores these dynamics among young Indigenous males is particularly scant. In turn, strategies to bridge health equity gaps have been obscured. This article brings together disparate research on health literacy, masculinities, youth studies and men’s health in order to address this oversight. By outlining the collective conceptual contribution of these strands of scholarship, we show that young Indigenous males navigate health literacy through a complex cultural interface that balances both Western and Indigenous understandings of health. Alternative masculine identities, which simultaneously embrace and resist components of hegemonic masculinity, also shape this health literacy lens. We explain that the development of health literacy is important for young people, particularly young Indigenous males, and that this is negotiated in tandem with external support structures, including family and friends. By describing these intersections, we explore the implications for researchers, policymakers and practitioners seeking to achieve the dual goal of improving health literacy and reducing health inequi-ties among this highly marginalised population